Powder coating or Anodization?
Easy choice......
Mate you really want to go with powder coating, my old Trucks on my skateboard (Destructo's) where anodized, and beleive me it does look nice, but it wron't last anywhere near as long as a powder coat.
Let me make some sense to you:
Firstly, if your forks are in a less than impressive state, have any chips, or the material is degrading, including the finish on them, then I would suggest you get them firstly Sand blasted, this process would get all cavaties and little annoyances out of the way, including the finish on them.
The sand is shot out at 400 miles an hour, the end result is the bare metal, to its purest state, then comes the powder coating........:)
For the powder coating, well it's the best setting, most even coat you can get. It's a slow process if you want it done properly, each coat is as even as you can get (hardly any undulations if any), it's put on very thinly,layer for layer until you get the desired finish, KTM use it on their frames, honnestly I couldn't advice you more for this, and the cost well, bargain something like £600 if you include both processes, maybe more, hope it works out for ya.